Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.
Bibliographic details of the publications referred to by author in this specification are collected alphabetically at the end of the description.
Worldwide, rotaviruses (RVs) are a major cause of diarrhea-associated morbidity and mortality in infants and young children. RV infection is responsible for more than 500,000 deaths annually, mainly in developing countries. The World Health Organization (WHO) has stated that development of a safe and effective vaccine is a priority (Bern and Glass (1994) Impact of diarrheal diseases worldwide In Kapikian AZ (ed) Viral Infections of the gastrointestinal tract, 2nd edition, New York Marcel Dekker, Inc.:1-26; Jiang et al. (2002) Clin Infect Dis 34:1351-1361).
In particular, RV cause acute gastroenteritis, a disease that requires hospitalization of infants and young children. Studies in the U.S., Australia, and Japan have demonstrated that between 34 and 63% of hospitalizations of children for acute diarrheal disease are associated with RV infection. The incidence of hospitalization for RV gastroenteritis in a health maintenance organization in the U.S. was estimated to be 222 per 100,000 in children from 13 to 24 months of age, and 362 per 100,000 in those less than one year. Infection with RV was associated with 63% of all hospitalizations for acute diarrhea in this pediatric population. A review of mortality data in the U.S. from 1973 to 1983 indicated that 500 deaths per year occur in children less than 4 years old due to diarrheal diseases, and that 20 to 80% of excess winter deaths due to diarrhea in the U.S. are associated with RV infections. RVs are also responsible for a substantial proportion of the mortality associated with diarrheal diseases in third world countries. An effective RV vaccine would, therefore, have a major impact on the health of children in both the developed and developing areas of the world.
RVs are non-enveloped icoshedral viruses whose capsid is formed by three concentric layers of viral protein (VP). The innermost layer is formed by 60 dimers of VP2 that surrounds the viral genome which is composed of 11 segments of double-stranded RNA and 12 copies of each of VP1 (the RV polymerase) and VP3 (the virus copping enzyme). The second layer of protein is formed by 280 trimers of VP6 which is located on top of VP2 to form double-layered particles (DLPs). Finally, the addition of 280 trimers of the glycoprotein, VP7, which constitute the outermost layer of the RV and 60 dimeric spikes of the VP4 protein to the DLPs, serve to form the triple-layered particles (TLPs) which represent the mature, infectious RV.
VP7 is an outer capsid protein. It is a glycoprotein and interacts with VP4 and VP6. Another group of proteins is the “non-structural proteins” (NSPs). NSP5, for example, has been proposed to have a structural role together with NSP2 in the assembly of viroplasms and for virus replication.
Sato et al. (1981) Arch. Virol. 69:155-160, described successful cultivation of human RVs from fecal specimens using roller cultures of MA104 cells (fetal kidney cells from Rhesus monkeys). However, MA104 cells are relatively uncharacterized, at least for use as vehicles for generating viruses for a vaccine. There is a need to develop a protocol for cultivating RV in a well characterized cell system for use in the development of an RV vaccine. There is also a need for the virus to be of sufficient titer to produce a protective immunological and response in subjects.